| Imported post
Hi there John,
I assume that you are querying the statement refering to the use of nitrox and the use of pseudoephedrine. Incidently, that post was done by Fee, don't worry she is not too upset :maniac: as there is only a bit of difference; 10 inches in height, 7 stone in weight and a hairy chest (wont tell you which one has the hairy chest). I first came across this notion during my PADI basic nitrox course and as I have the view that you should dive as safely as possible I just accepted it and if I have to use a decongestants I use one that doesn't contain pseudoephedrine. Since then I have had a bit of a literature search and found a study study that does suggest a link between ephedrine and increased utilisation of oxygen and thus a tenuous link to ox-tox, how closely this pertains to diving I wouldn't like to guess but there is a hint that maybe we shouldn't dive nitrox using it.
The study involved bolus doses of ephedrine which are often used by anaesthesetists for intraoperative hypotension. The study was randomized single-blind cross-over study (for all you science monkeys out there) was designed to simultaneously evaluate circulatory, respiratory and metabolic effects of intravenously given ephedrine in 12 healthy male volunteers. Oxygen uptake and carbon dioxide excretion were measured with indirect calorimetry and non-invasive transthoracic electrical bioimpedance was used for cardiac output measurements. The maximum effect on most variables was reached at 4-5 min. At 5 min after the administration of ephedrine 0.1 mg per kilogram body weight, there were significant increases in cardiac index, systolic and mean arterial blood pressure, expired minute volume, oxygen uptake and carbon dioxide excretion rates. There were no significant changes in the quotient between oxygen uptake rate and cardiac index, VO2/CI during the 30 min study period. The O2 saturation was not altered. The present study indicates that ephedrine increases oxygen demand and supply in a similar magnitude.
HTH :umnik: here endeth the lesson :yelclap:
Ian Daly :doctor:
(Edited by Ian Daly at 9:27 am on Feb. 9, 2003)
(Edited by Ian Daly at 11:04 am on Feb. 13, 2003)  |